Have a friends 20-20 here with a tube issue. First, anyone with an accurate schematic or know where to get it? Second, I looked at the amp a while back and what it did was after 15 or so minutes V6 (el84) would glow bright red like a shorted tube. Changed out and suggested he order a new round of tubes. Problem seemed solved. But I spoke with him yesterday and he purchased a new matched set of Mesa tubes from a local retailer and swapped them out and said the amp works fine when started but after 15 minutes or so the EL84 V6 gets extremely hot and glows brightly. It happens like clockwork even though it is a new set of tubes. (same things as with old tubes). Turn it off and let it cool down and results are the same every time.
I can find no bad resistors or burnt traces or shorts. Any ideas on what to look at. Only one of that pair acts this way.
About to fire it up and do voltage checks although under load and see if I can find an intermittent resistor as it occurs. New one on me.
I can find no bad resistors or burnt traces or shorts. Any ideas on what to look at. Only one of that pair acts this way.
About to fire it up and do voltage checks although under load and see if I can find an intermittent resistor as it occurs. New one on me.
